Such was the litany of despair recited in Latin by the monks when a Viking longship loomed out of a meander on the river Seine. The Vikings, these Northmen, these Norman, pillaged the abbey of Jumièges in 841. The raid was not enough to take away all the riches of this affluent monastery, which, according to the legend, was home to 900 monks, so they came again a few years later.

Do things always come in threes? Rather than waiting to see if the proverb came true, the monks then took to their heels and deserted for 50 years this Carolingian abbey founded in 654 by Saint Philibert.

The fury of these Northmen is the same as all the conquistadors with a thirst for gold and blood, running with their swords in their hands towards the Eldorado. Because with its thriving agriculture, its trade, its waterways, its abbeys full of gold and gemstones and its frightened monks, this is what the Jumièges abbey and the Seine valley were in the Middle-Ages: an Eldorado.

Of this Norman fury that used to terrorize the religious community, there is nothing left: we came from Rouen by car and saw nothing but a peaceful lifestyle and quiet orchards full of apples, pears and cherries. By the way, this short trip has convinced me: we will come back in summer to follow the Fruit Trail. Why not by bike?

In the meantime, we have chosen to visit a heritage site: the Jumièges Abbey because we were told there was a guided tour with augmented reality...

'The first monastery, founded during the Carolingian period, was burnt down by the Vikings', the guide started to say. 'The buildings you can see here mostly date back to the 11th century. And when the conventual church Notre-Dame de Jumièges was consecrated, the entire Norman aristocracy and William the Conqueror, Duke of Normandy, were present. Yet, the Norman aristocracy and the dukes of Normandy were themselves descended from the Vikings. The Vikings pillaged and burnt down Jumièges, the Normans restored it!'

Julie, who was half-listening, frowned: funny people those Vikings; they destroy churches to rebuild them a few years later!

But she couldn't take her eyes off the guide's tablet. She was watching it attentively, like a cat waiting for food. This is actually how I persuaded my daughter to visit this place. I just had to say the magic words: augmented reality, 3D, touchscreen tablet! And she clearly knew better than I did what they meant... Well, architecture, abbeys and Vikings, OK, they may be fun, but when do we play with the tablet?

'So, over one thousand years ago, this ground where we are walking was trodden by monks', the guide continued. 'Our abbey destroyed...'

Our abbey? Clara and I exchanged knowing smiles: I had never heard a guide talk like that about a historic building.

But to hear him talk about it in such an animated way, so passionate and possessive, all of a sudden I understood this habit of naming churches. Notre-Dame means Our Lady: cathedral builders, parishioners and our guide, all say it instinctively and share the same jealous and desirous sense of pride. Our cathedral, our church, our Jumièges abbey.

In fact, as I looked at him closely, I realised there was something monastic about our guide!

In his austere attitude that lights up only when he talks about his abbey, in his almost ecstatic passion he devotes to these old stone buildings, in the way he walks, day after day, in the footsteps of the monks who strode the nave, church, cloister and scriptorium for one thousand years.

Just like the monks who used to organise their day around the seven daily prayers, I guess he punctuates his day with the visits, preaching the architectural wonders of his abbey, which deserves all the superlatives: it is the biggest, the wealthiest and, of course, the most beautiful. He hardly admits that Amiens is a few metres higher - a peccadillo...

After going through the abbey's history and its misfortunes, he described the different architectural influences and, finally much to my relief, turned on his tablet. It was about time: Julie was about to tug at his sleeve to ask him how long it would be before he used it... As he lifted it up, like one raises a monstrance, we all gathered around him. And a different reality appeared, like another hidden world suddenly materializing from the past.

In front of us, these ruins, already impressive, transformed themselves into a majestic building, an ancient basilica.

Following the guides movements, the architectural genius of the Norman duchy, then at the height of its power, unfolded live before our eyes: 46-metre-high (150 ft.) towers and 25-metre-high (82 ft.) walls. The 3D image overlays the real view in real time, as if it was in a waking dream. Our eyes moved back and forth from the screen to the landscape, to distinguish what was real from what has been recreated by computer…

This technological challenge is consistent: what we have learnt during this visit is that Jumièges has always been at the cutting edge of technology. It explains why there is a combination of different architectural styles, which is certainly the essential quality of the place. Throughout history, Romanesque, Gothic and Classical additions were built on the original Carolingian foundations. The church summarises this unceasing improvement: the light fills the Romanesque choir through large openings created thanks to the Gothic load-bearing techniques. The Gothic pointed arches have also been renovated. One of them is Romanesque and even has a Gothic ribbed vault. Just to look more modern! Because this alteration, in terms of load-bearing, serves absolutely no purpose.

The entire monastery has thus been improved without destroying the older parts. The walls, for instance, are Gothic but the façade, on the other hand, is a combination of Gothic and Romanesque architectures.

Clara put her hand on Julie's shoulder, interrupting her fascination for the 3D images.

'Did you see?'

'What?'

'There, at the top of the column, on the left, look! Does it remind you of something?'

Clara is pointing at a small fresco: a human figure who seems to spit a tree leaf.

The tablet also did wonders in the cloister, of which there is not much left: during the French Revolution, the abbey was sold and demolished for its stones. The building was so solid that they even had to blow up the parts that resisted. The abbey was bought by a banker in 1852 who kept it as it was. When he created an English garden around the abbey he gave it the tag "most beautiful ruin in France".

"From the fury of the Northmen deliver us, O Lord!"

As we walked out of the abbey, with these huge white towers standing out in the middle of orchards and these fields hardly skimmed by the meanders of the river Seine, I understood that the prayers of the monks had finally been answered: yes, Normandy has definitely delivered the Normans from their own fury.

The Seine Valley has charms to soothe the savage breast; it's a conversion into gentleness and tolerance that takes time: instead of killing everybody, they put away their axe and bow, their sword and shield. And, finally at peace, they have grown fruits in the shadow of the abbeys. They became monks to reflect on the beauty of the world, peasants to cultivate the land, or guide to talk about it...